The present invention relates to photochromic indenochromene derivatives and the use thereof in plastics of all types, particularly for ophthalmic applications. In particular, the present invention relates to specific photochromic heterocyclically annellated indeno[2,1-f]chromene derivatives and specific photochromic,  heterocyclically annellated indeno[1,2-h]chromene derivatives.
There are various known classes of dyes that reversibly change their color when irradiated with light of certain wavelengths, particularly sun light. This is due to the fact that these dye molecules change into an excited colored state when supplied with energy in the form of light. They leave this state again when the energy supply is interrupted, and thereby return to their colorless or at least their hardly colored normal state. These photochromic dyes include, for instance, naphthopyrans with various substituents, which have previously been described in the prior art.
Pyrans, especially naphthopyrans and larger ring systems derived therefrom, are photochromic compounds, which to this day continue to be the subject of intensive research. Although a first patent application (U.S. Pat. No. 3,567,605) was filed as early as 1966, it was not until the nineties that compounds, which appeared suitable for the use in eyeglasses, were developed.
Heterocyclically annellated benzopyrans are known, for instance, from U.S. Pat. No. 5,631,720. Relatively minor structural changes in the heterocycle have an enormous influence on the lightening rate (a factor of about 5). The compounds described in U.S. Pat. No. 5,631,720, however, have the drawback that they only cover the range from about 430 to 450 nm (absorption maximum of the excited form), i.e., only orange to red tints may be obtained.
WO 98/28289 describes compounds that supply dull red to red-violet tints, but the bathochromic effect of the substitution compared to 2 methyl groups is low at 25 nm. The influence on the lightening kinetics is negative, with the lightening rate being slightly retarded in all cases. The specified structure allows only substitutions that have hardly any effect on the lightening rate. Fluoreno- and naphthopyrans, which provide red-violet to green tints are known, for instance, from WO 99/15518 and DE 198 24 278 or DE 199 02 771. They are distinguished by their excellent long-term stability and good temperature stability (little dependence of the darkening depth on the temperature). The possible substitutions described therein, however, allow comparatively little latitude with respect to the lightening rate.
The introduction of a heterocyclic component by replacing the central C atom of the fluorene structure by N-R as proposed in WO 99/23071 results in compounds whose absorption maximum in the non-excited state is around or above 400 nm, i.e., clearly within the visible range. However, since the absorption extends beyond the maximum far into the violet and blue spectral region, compounds with a strong yellow tint in their non-excited state are obtained. They are therefore not suitable for use in eyeglasses.
Likewise disadvantageous is the introduction of a heterocyclic unit on the two benzene rings of the indenonapththopyran structure as described in U.S. Pat. No. 5,698,141 and U.S. Pat. No. 5,723,072. The darkening depth of these compounds (usually given as colorability A0) is low compared to the compounds of U.S. Pat. No. 5,631,720. In addition, compounds with very many annellated rings are obtained, which for the most part clearly absorb in the visible range in their non-excited state, i.e., the compounds are yellow in their non-excited state. Insofar as the compounds in their excited state show an absorption maximum in the range of 576-600 nm, i.e., a blue excitation color, green compounds are obtained, which are generally not very suitable for use in eyeglasses.
U.S. Pat. No. 5,645,767 and U.S. Pat. No. 5,869,658 describe the positive effect on the photochromic properties of indeno fusing to the f-side of the naphthopyran system. The compounds generally show longerwave absorption and increased darkening performance. EP-A-0 987 260 and DE 199 30 290 describe systems in which the indene unit is integrated in a spiro structure. These compounds are distinguished by excellent durability and rapid lightening rates with simultaneous good darkening performance.
The darkening tint of the aforementioned systems described in the prior art depends primarily on the substituents at the 3-position in 3H-naphtho[2,1-b]pyrans or, on the substituents at the 2-position in 2H-naphtho[1,2-b]pyrans. For technical applications, cosmetically neutral darkening tints, such as brown or gray, are preferred. The aforementioned compound systems have strong tints, however, so that only mixtures of different dyes can be used.
Thus, the object of the present invention is to provide novel photochromic systems, which, in contrast to the compounds thus far available in the prior art, should have broader absorption bands for duller tints, i.e., they should, in particular, exhibit cosmetically neutral darkening tones. In addition, these compounds should exhibit rapid lightening with simultaneous good darkening performance and good durability.
This object is achieved by the substances characterized in the claims. In particular, photochromic heterocyclically annellated indeno[1,2-h]chromenes having the general formula (I) and indeno[2,1-f]chromenes having the general formula (II) are provided: 
wherein
the groups R1 and R2 independently from each other represent a substituent selected from group A consisting of hydrogen, fluorine, chlorine, bromine, a hydroxy group, a (C1-C6) alkyl group, a (C1-C6) alkoxy group, a (C3-C7) cycloalkyl group which may have one or more heteroatoms, a (C1-C6) acyl group, an unsubstituted or monosubstituted phenyl group and an unsubstituted or monosubstituted benzyl group, wherein their substituents are selected from the group consisting of a (C1-C6) alkyl group and a (C1-C6) alkoxy group;
or the groups R1 and R2 together represent an annellated, unsubstituted, monosubstituted or disubstituted benzo or pyrido ring whose substituents are selected from group A;
group R3 represents a substituent selected from among hydrogen, a (C1-C6) alkyl group and xe2x80x94OM, wherein M is a substituent selected from group A;
group R4 is a substituent selected from among hydrogen, a hydroxy group, a (C1-C6) alkyl group, a (C1-C6) alkoxy group, a (C3-C7) cycloalkyl group, a (C1-C6) acyl group, a respectively unsubstituted, mono-, di- or trisubstituted phenyl group, benzyl group, naphthyl group, phenanthryl group, pyrenyl group, quinolyl group, isoquinolyl group, benzofuranyl group, thienyl group, benzothienyl group, dibenzofuranyl group, dibenzothienyl group, carbazolyl group or indolyl group, wherein their substituents are selected from group A, a (C1-C6)-xcfx89-phenylalkyl group and a (C1-C6)-xcfx89-phenoxyalkyl group, wherein the phenyl ring in the xcfx89-position in turn may be part of another photochromic pyran system;
or the groups R3 and R4 including the central spiro carbon atom together represent a saturated and/or unsaturated ring member with 5 to 8 carbon atoms of which maximally one may be substituted by a heteroatom selected from the group consisting of O, S and NR5, wherein group R5 is selected from group A, and wherein at least one aromatic or heteroaromatic ring system is fused to the ring member, wherein the ring system is selected from group E consisting of benzene, naphthalene, phenanthrene, pyridine, quinoline, furan, thiophene, pyrrole, benzofuran, benzothiophene, indole and carbazole, and the ring system may have one or more substituents from group A;
the annellated heterocycle (Het) represents a 5 or 6-membered heteroaromatic ring cycle corresponding to the following general formulas: 
xe2x80x83wherein Y is selected from among oxygen, sulfur and NR5, and Z, U, V and W independently from each other are selected from among nitrogen and CR6, wherein groups R6 and R7 independently from each other represent a substituent from group A, or groups R6 and R7 if they are ortho to each other together represent an unsubstituted or monosubstituted benzene ring whose substituents are selected from group A; and B and Bxe2x80x2 are selected independently from each other from one of the following groups a), b), c) or d), wherein
a) they are mono-, di- and trisubstituted aryl groups, wherein the aryl group is phenyl or naphthyl;
b) they are unsubstituted, monosubstituted and disubstituted heteroaryl groups, wherein the heteroaryl group is pyridyl, furanyl, benzofuran-2-yl, benzofuran-3-yl, thien-2-yl, thien-3-yl, benzothien-2-yl, benzothien-3-yl, phenazinyl, phenoxazinyl, phenothiazinyl or julolidinyl;
wherein the substituents of the aryl or heteroaryl groups in a) and b) are those selected from the group consisting of the above-defined group A, hydroxy, amino, mono-(C1-C6) alkylamino, di-(C1-C6) alkylamino,
mono- and diphenylamino which are unsubstituted, monosubstituted or disubstituted on the aromatic, wherein their substituents in turn are selected from group A, pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, phenazinyl, phenoxazinyl, phenothiazinyl, carbazolyl, unsubstituted, mono- and disubstituted pyrryl, wherein its substituents are selected from group A,
c) they are structural units with the following structural formulas (B) and (C): 
xe2x80x83wherein
D and E independently from each other represent oxygen, sulfur, carbon or NR8, wherein the groups R8, R9, R10 and R11 independently from each other represent a substituent from group A, wherein n represents 1, 2 or 3, provided that, if D is NR8 in formula (B), E represents carbon (i.e., methine (xe2x95x90CH) or methylene (CH2)),
or
d) B and Bxe2x80x2 together form an unsubstituted, monosubstituted or disubstituted fluorene-9-ylidene group or a saturated hydrocarbon group, which is C3-C12 spiro-monocyclic, C7-C12 spiro-bicyclic and/or C7-C12 spiro-tricyclic, wherein the fluorene substituents are selected from group A.
The heterocyclically annellated indeno[2,1-f]chromene derivatives according to the invention may be considered heterocyclic relatives of 3H-naphtho[2,1-b]pyrans, and the heterocyclically fused indeno[2,1-f]chromene derivatives according to the invention as heterocyclic relatives of 2H-naphtho[1,2-b]pyrans.
In a preferred embodiment, the annellated heterocycle (Het) is an indole unit, a benzofuryl unit, a benzothienyl, a thienyl unit, a furyl unit, an oxazolyl unit, an imidazolyl unit, a pyrimidinyl unit, a pyrazinyl unit or a triazinyl unit, wherein, in the case of an indole unit, a benzofuryl unit or a benzothienyl unit, annellation to the indenochromene skeleton takes place via the 5-membered heterocycle. Particularly preferably, the annellated heterocycle (Het) is an indole unit, a benzofuryl unit, a benzothienyl, a thienyl unit or a furyl unit.
In one embodiment B and Bxe2x80x2 independently from each other represent mono-, di- or trisubstituted phenyl groups, wherein the substituents are those selected from the group consisting of the above-defined group A, hydroxy, amino, mono-(C1-C6) alkylamino, di-(C1-C6) alkylamino, mono- and diphenylamino, which are unsubstituted, monosubstituted or disubstituted on the aromatic, wherein their substituents in turn are selected from group A, pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, phenazinyl, phenoxazinyl, phenothiazinyl, carbazolyl, unsubstituted, monosubstituted and disubstituted pyrryl, wherein its substituents are selected from group A. In another embodiment B and Bxe2x80x2 independently from each other represent a julolidinyl group.
Particularly preferred compounds according to the present invention are:
2-(2-fluorophenyl)-2-phenyl-2,14-dihydro-[1]benzofuro[2,3-f]indeno[1,2-h]chromene,
2-(2-fluorophenyl)-2-(4-methoxyphenyl)-2,14-dihydro-[1]benzofuro[2,3-f]indeno[1,2-h]chromene,
2-(2-fluorophenyl)-2-(4-(4-morpholinyl)phenyl)-2,14-dihydro-[1]benzofuro[2,3-f]indeno[1,2-h]chromene,
2-(2-fluorophenyl)-2-phenyl-2,14-dihydro-[1]benzothieno[3,2-f]indeno[1,2-h]chromene
2-(2,4-dimethylphenyl)-2-phenyl-2,14-dihydro-[1]benzothieno[3,2-f]indeno[1,2-h]chromene, 2-(2-fluorophenyl)-2-(4-methoxyphenyl)-2,14-dihydro-[1]benzothieno[3,2-f]indeno[1,2-h]chromene,
2-(2-fluorophenyl)-2-phenyl-2,12-dihydroindeno[1,2-h]thieno[2,3-f]chromene
2-(2-fluorophenyl)-2-phenyl-9-methyl-2,9-dihydro-14H-indeno[1,2-h]indolo[3,2-f]chromene and
spiro-9-fluorene-12xe2x80x2-[3,3-diphenyl-3,12-dihydroindeno[2,1-f]-thieno[2,3-h]chromene].